Puffy Cube revisited

Honestly I was overwhelmed with the response to the puffy cube challenge. I want to thank everyone who sent in a model or comments. There were a total of 31 responses, and I turned away a couple Solid Edge entries. I learned a lot of stuff, and noticed a few things about how people model and maybe even think.

The part originated in a surfacing class I used to give years before the surfacing book came out, and also by a disastrous demo I did for a group of Xerox ID folks many years ago. The demo was basically to make a box in such a way as to tug and pull the edges and faces. Of course I didn’t learn that until I had failed the test. It was a “do this, do that, now make it change some other way” sort of test, so I couldn’t really avoid failure. I equated the design they were looking for with a “smurf” house – you know, where everything is round and made of blue and white marshmallows. Anyway, the puffy cube became a way to represent something that looked easy, and maybe “should” be easy, but certainly wasn’t straight forward.

First, when I looked at this part, I saw a great excuse to do surface modeling. Several of you saw it as a solid with boolean operations. Almost everyone approached this with some sort of pattern, usually two patterns, or a pattern and a mirror. My initial model was like Mark Landsaat’s, where I revolved a surface, patterned it around, then trimmed it and made it solid. I guess the reason I did it that way is that after doing so much surface modeling, I tend to think of parts as consisting of individual faces.

Entry 4 from Clay Corbett skipped the pattern altogether using a pair of lofts from 3D sketches and a knit. Entry 26  from Mike Wilson used a Move/Copy Bodies rather than a pattern, and Entry 30 from Pilun Chen used a curve driven pattern to overcome the need for multiple patterns.

Another trend that I liked was that people are beginning to get the hang of the Boundary surface. In most cases, boundary can be used as a direct replacement for loft. There are very few places where lofts can achieve something a boundary cannot (the exceptions being centerline lofts, closed loop lofts without direction2 curve). Chris Cole and Brian McElyea made good use of the Fill surface.

Several folks also used surface bodies as reference geometry, which is a use of surfaces that I like to promote amongst solids users. Mike Wilson used a surface as an Extrude Up To reference. Others used surfaces for their edges or to create curves.

Entry 29 from Matt Cummins was the only one to use partner software to achieve changes. Matt works for Tacton Works, a knowledge based engineering software vendor. I think Matt’s example shows the strength of KBE for work of this sort.

Many of you used 3D sketches in a way I wouldn’t have thought of. The first thing I learned about 3D sketch was that you can combine a lot of things that would otherwise take several 2D sketches into a single 3D sketch. Of course this makes the 3D sketches much more complex. Most of these techniques used planes inside the 3D sketch. 3D sketch planes can sometimes be difficult to control if your sketch is underdefined.

Pilun Chen (entry 30) gets points for the successful utilization of a curve driven pattern. I thought this was a very creative approach to solve the patterning/mirroring issue.

Clay Corbett and I tied for use of least features. I think Pilun Chen’s model could have been reduced by a sketch with a little effort.

For breaking the rules, I liked Mark Kaiser’s model with the straight edges, and several of the solids approaches.

The most novel approach I have to give to Pilun Chen for that curve driven pattern.

What did you learn from this exercise?

PS: the next challenge will be posted in the next week before SolidWorks World.